He was probably baptized by Bartholomeus Boekbinder or Willem de Kuyper, emissaries of Jan Matthys.
Hoffman introduced the first self-sustaining Anabaptism to the Netherlands, when he taught and practiced believers' baptism in Emden in East Frisia.
Around 1560, Philips wrote his Confession: Recollections of the Years 1533–1536, which was published after his death by Cornelius Claesz.
In it he wrote, "I am still miserable of heart today, that I...was so shamefully and miserably deceived...I did not stop forthwith but permitted myself to bring poor souls to this—that I through the importuning of the brethren, commissioned to the office: Dietrich Philips in Amsterdam; David Joris in Delft; and Menno Simons in Groningen...It is this which is utter grief to my heart, and which I will lament before my God as long as I live..." He was dubbed a Demas by Menno (after the disciple Demas, who forsook the Apostle Paul).
In his Confession he spoke harshly against revolutionaries and false prophets, but not against the peaceful Anabaptists such as followed Menno.